In the field of olefin production, a process to selectively produce high purity 1-hexene from the trimerization of ethylene involves the separation of an oligomerization reactor effluent into four major streams: product, unconverted ethylene, recovered solvent, and heavies. Typically the separation of the oligomerization reactor effluent to obtain high purity 1-hexene can be achieved with three distillation steps operated in series, wherein the first distillation column separates the ethylene from the remaining constituents in the bottoms that then becomes the feed for a second column, wherein the product is stripped off and a distillate of high purity 1-hexene is obtained. The bottoms become the feed for a third distillation column, wherein the heavies/solvent split is made. Multiple separation steps such as these involving distillation columns can be costly. Therefore, a need exists for process improvements to separate oligomerization reactor effluent.